This is proving a really exciting project for me as I contemplate my coastal strips and harbour project.
You have reminded me of some technique of polystyrene work which had been pushed to the back of my memory since I last did one of these some years ago now.
You are both quite right about the height of objects.
I also make them slightly brighter than in real life when I paint them to make the contrast with shadowed areas more pronounced. I find that this also helps with the deception.
Rob.